1. Field
Example embodiments relate to a test device, SRAM test device, a semiconductor integrated circuit device, and methods of fabricating the same. Other example embodiments relate to a test device, an SRAM test device, a semiconductor integrated circuit device, and methods of fabricating the same with improved productivity.
2. Description of the Related Art
Static random access memories (SRAMs) have a smaller memory capacity than dynamic random access memories (DRAMs), but a faster operation speed than the DRAMs. Accordingly, SRAMs are used in cache memories of computers or portable appliances where relatively high-speed operations are required.
SRAM cells are divided into thin film transistor cells (TFT cells) and/or full complementary metal oxide semiconductor cells (FCMOS cells). The FCMOS cells may include a plurality of pull-up and pull-down transistors that constitute a latch and a plurality of pass transistors to access the latch.
With the relatively high integration of a semiconductor memory device, memory cells are increasingly becoming smaller. As the size of the memory cells decreases, the size of metal contacts may also decrease. However, because the size of the metal contacts decreases, accurately patterning the metal contacts may become difficult, resulting in an increase in defective contacts. Therefore, it is very important to confirm and test whether contacts are securely formed and an upper region and a lower region of the semiconductor memory device are electrically connected to each other (e.g., whether the contacts open).
One method for testing whether contacts open in an SRAM device is a method using an electronic beam (E-beam). However, when using an electronic beam, a relatively large amount of time may be needed to perform the test, and productivity may be lowered. Further, a noise may occur due to instability of an electronic beam facility.
Another method for testing whether contacts open in the SRAM device is a method in which a test element is separately formed. Because the structures of the test element and an actual cell element are different, it may not be possible to accurately determine whether a contact opens in the cell element, even when the test element is used. For example, even though a test contact of the test element opens, the contact of the cell element may not open. In contrast, even though the test contact of the test element may not open, the contact of the cell element may open. As a result, the test may not be accurately performed, which results in lower productivity.